Hello Luzie!So this feature only for loading iSDOS/TASiS operation system (it not compatible with FAT and have itself FAT format) from HDD.You can read about iSDOS\TASiS hier: http://atmturbo.nedopc.com/projects/os_prj.htm (use google translate to translating from russian).Maksagor is chief of TASiS project, you can ask him direct.

Easy way to using HDD:1) Format it to FAT32 (on PC)2) Copy some *.trd, *.scl diskette-images files (for example from vtrdos.ru)3) Start it from "File browser" on ZXEVO